Methods and apparatus for implementing connectivity between edge devices via a switch fabric

ABSTRACT

In some embodiments, an apparatus includes a first edge device that is operatively coupled to a second edge device via a switch fabric. The first edge device and the second edge device collectively define an edge device network operating with a network-address-based protocol. The first edge device communicates with the second edge device via a multiprotocol label switching (MPLS) tunnel through the switch fabric. Furthermore, the first edge device is operatively coupled to the switch fabric such that a node of the switch fabric can be modified without coordination of the edge device network. Additionally, the first edge device is operatively coupled to the second edge device to define the edge device network such that an edge device of the edge device network can be modified without coordination of the switch fabric.

PRIORITY TO RELATED APPLICATION

This application claims priority to and is a continuation of U.S.application Ser. No. 14/042,015, (now U.S. Pat. No. 9,419,892), entitled“METHODS AND APPARATUS FOR IMPLEMENTING CONNECTIVITY BETWEEN EDGEDEVICES VIA A SWITCH FABRIC” and filed Sep. 30, 2013, the content ofwhich is incorporated herein by reference in its entirety.

BACKGROUND

Some embodiments described herein relate generally to methods andapparatus for implementing connectivity between edge devices in an edgedevice network via a switch fabric. In particular, but not by way oflimitation, some embodiments described herein relate to methods andapparatus for implementing connectivity between edge devices in an edgedevice network operating with a network-address-based protocol via theswitch fabric that maintains administrative, control plane, data planeand/or addressing separation between the edge devices and the switchfabric devices.

Some known switch fabrics include edge devices that offer services andswitch fabric devices that offer connectivity among the edge nodes andto other networks. Such known switch fabrics typically do not separatebetween the edge devices and the switch fabric devices foradministration and/or operation. For example, the edge devices can besubject to administrative coordination with adjacent switch fabricdevices. Such an approach of administrating and operating the edgedevices and switch fabric devices, however, can produce a risk ofadversely affecting the switch fabric and cause security vulnerabilityfor the switch fabric. Furthermore, the edge devices and switch fabricdevices are often managed by different groups.

Accordingly, a need exists for methods and apparatus for implementingconnectivity between edge devices in an edge device network operatingwith a network-address-based protocol via the switch fabric thatmaintains administrative, control plane, data plane and/or addressingseparation between the edge devices and the switch fabric devices.

SUMMARY

In some embodiments, an apparatus includes a first edge device that isoperatively coupled to a second edge device via a switch fabric. Thefirst edge device and the second edge device collectively define an edgedevice network operating with a network-address-based protocol. Thefirst edge device communicates with the second edge device via amultiprotocol label switching (MPLS) tunnel through the switch fabric.Furthermore, the first edge device is operatively coupled to the switchfabric such that a node of the switch fabric can be modified withoutcoordination of the edge device network. Additionally, the first edgedevice is operatively coupled to the second edge device to define theedge device network such that an edge device of the edge device networkcan be modified without coordination of the switch fabric.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic illustration of a switch fabric system thatconnects edge devices via a switch fabric, according to an embodiment.

FIG. 2 is a system block diagram of an edge device, according to anembodiment.

FIG. 3 is a system block diagram of a switch fabric device, according toan embodiment.

FIG. 4 is a flow chart illustrating a method for communication betweenedge devices via a switch fabric, according to an embodiment.

DETAILED DESCRIPTION

In some embodiments, an apparatus includes a first edge device that isoperatively coupled to a second edge device via a switch fabric. Thefirst edge device and the second edge device collectively define an edgedevice network that operates with a network-address-based protocol. Sucha network-address-based protocol can be, for example, an interiorrouting protocol (IGP), label distribution protocol (LDP), bordergateway protocol (BGP), resource reservation protocol-trafficengineering (RSVP-TE) protocol, and/or the like. In such embodiments,the first edge device communicates with the second edge device via amultiprotocol label switching (MPLS) tunnel through the switch fabric.

Furthermore, the first edge device is operatively coupled to the switchfabric such that a node of the switch fabric can be modified withoutcoordination of the edge device network. Similarly, the first edgedevice is operatively coupled to the second edge device to define theedge device network such that an edge device of the edge device networkcan be modified without coordination of the switch fabric.

In some instances, the first edge device can be configured to send arequest according to an auto-discovery protocol to a first switch fabricdevice of the switch fabric. Such an auto-discovery protocol can be, forexample, dynamic host configuration protocol (DHCP), address resolutionprotocol (ARP), Radius (remote authentication dial-in user service)protocol, Diameter protocol, trivial file transfer protocol (TFTP), linklayer discovery protocol (LLDP), and/or the like. The first edge devicecan be configured to receive a response according to the auto-discoveryprotocol and in response to the request. The response can include alabel associated with the first edge device. Furthermore, the firstswitch fabric device can send to a second switch fabric device of theswitch fabric, according to at least one MPLS protocol, an advertisementindicating the label. The MPLS protocol can be, for example, LDP,RSVP-TE, BGP, and/or the like.

After receiving the response, the first edge device can be configured tosend to the second edge device the label such that the MPLS tunnel isestablished between the first edge device and the second edge devicebased on the label. In some instances, the first edge device can beconfigured to send the label to the second edge device according to BGP.In some instances, the first edge device and the second edge device cancommunicate with the switch fabric via auto-discovery messages withoutany other protocol message (e.g., any network-address-based protocolmessage).

In some embodiments, an apparatus includes a switch fabric device thatis included within a switch fabric operatively coupled to an edge devicenetwork. The edge device network operates with a network-address-basedprotocol such that edge devices of the edge device network cancommunicate via, for example, a set of MPLS tunnels through the switchfabric. In such embodiments, the switch fabric device can be modifiedwithout coordination of the edge device network. Similarly, edge devicesof the edge device network can be modified without coordination of theswitch fabric.

In some embodiments, an apparatus includes a first edge deviceoperatively coupled to a switch fabric that is coupled to a second edgedevice. The first edge device communicates with the second edge devicevia an MPLS tunnel through the switch fabric. In such embodiments, thefirst edge device is also operatively coupled to the second edge deviceto define an edge device network such that an edge device of the edgedevice network can be modified independent of the switch fabric and anode(s) of the switch fabric can be modified independent of the edgedevice network.

As used in this specification, the term “physical hop” can include aphysical link between two nodes and/or devices. For example, a data pathoperatively coupling a first node with a second node can be said to be aphysical hop. Similarly stated, a physical hop can physically link thefirst node with the second node.

As used in this specification, the term “single physical hop” caninclude a direct physical connection between two nodes and/or devices ina system. Similarly stated, a single physical hop can include a link viawhich two nodes are coupled without intermediate nodes. Accordingly, forexample, if a first node is coupled to a second node via a singlephysical hop, the first node can send data units (e.g., data packets,data cells, etc.) directly to the second node without sending the dataunits through intervening nodes.

As used in this specification, a module can be, for example, anyassembly and/or set of operatively-coupled electrical componentsassociated with performing a specific function, and can include, forexample, a memory, a processor, electrical traces, optical connectors,software (stored in memory and/or executing in hardware) and/or thelike.

As used in this specification, the singular forms “a,” “an” and “the”include plural referents unless the context clearly dictates otherwise.Thus, for example, the term “a tunnel module” is intended to mean asingle module or a combination of multiple modules collectivelyconfigured to perform a function of tunneling data.

FIG. 1 is a schematic illustration of a switch fabric system 100 thatconnects edge devices (e.g., edge devices 150, 162, 164, 170, 180) via aswitch fabric 105, according to an embodiment. The switch fabric system100 includes the switch fabric 105 and an edge device network 145. Theswitch fabric 105 includes one or more switch fabric devices such as theswitch fabric devices 110, 120, 130 and 140. The edge device network 145includes one or more edge devices such as the edge devices 150, 162,164, 170 and 180. In some embodiments, although not shown in FIG. 1, theswitch fabric 105 can include more or less switch fabric devices thanthose shown in FIG. 1; the edge device network 145 can include more orless edge devices than those shown in FIG. 1.

In some embodiments, the switch fabric system 100 can be implemented invarious locations and environments, and/or for different functions. Forexample, the switch fabric system 100 can be implemented at a datacenter, where the switch fabric 105 functions as the data center networkand the edge device network 145 includes servers of the data center. Foranother example, the switch fabric system 100 can be implemented as anaccess network, where the switch fabric 105 is a metropolitan areanetwork (MAN) and the edge device network 145 includes MPLS-enabledDSLAMs (digital subscriber line access multiplexers), eNodeBs (e-utrannode B, or evolved node B), OLTs (optical line terminations), and/or thelike. For yet another example, the switch fabric system 100 can beimplemented as a service network, where the switch fabric 105 is a widearea network (WAN) and the edge device network 145 includes provideredge (PE) nodes.

Each edge device from the edge device network 145 is coupled to at leastone switch fabric device from the switch fabric 105. For example, asshown in FIG. 1, the switch fabric device 110 is coupled to the edgedevices 150 and 164; the switch fabric device 120 is coupled to the edgedevice 170; the switch fabric device 130 is coupled to the edge devices162 and 164; and the switch fabric device 140 is coupled to the edgedevice 180. In some embodiments, although not shown in FIG. 1, eachswitch fabric device from the switch fabric 105 can be operativelycoupled (e.g., via MPLS tunnels) to each remaining switch fabric devicefrom the switch fabric 105. Thus, each edge device from the edge devicenetwork 145 can be operatively coupled to each remaining edge devicefrom the edge device network 145 via the switch fabric 105.

Each edge device of the edge device network 145 can be any deviceconfigured to be operatively coupled to the switch fabric 105. Such anedge device can be, for example, a compute node, server, router, accessswitch, gateway, and/or the like. In some embodiments, an edge devicecan be an input node, an output node, a top-of-rack (TOR) device, and/orthe like. In some embodiments, an edge device can function as both asource edge device and a destination edge device for data transmission.In some embodiments, although not shown in FIG. 1, an edge device of theedge device network 145 can be coupled to one or more peripheralprocessing devices or customer nodes. In such embodiments, the edgedevice can operatively couple the peripheral processing device(s) to theswitch fabric 105. The edge device can send data units (e.g., a streamof data packets and/or data cells) to and receive data units from theswitch fabric 105, and to and from the coupled peripheral processingdevice(s).

The peripheral processing devices (not shown in FIG. 1) that can beconnected to the edge devices of the edge device network 145 caninclude, for example, servers, storage devices, gateways, workstations,and/or the like. The peripheral processing devices can be operativelycoupled to one or more ports of the edge devices using any suitableconnection such as, for example, an optical connection (e.g., an opticalcable and optical connectors), an electrical connection (e.g., anelectrical cable and electrical connectors) and/or the like. Similarlystated, each port of the edge device can provide a communicationinterface through which a peripheral processing device can beoperatively coupled to that edge device. As such, the peripheralprocessing devices can send data units to and receive data units fromthe edge devices. In some instances, the connection between theperipheral processing devices and the edge devices can be a direct link.Such a link can be said to be a single physical hop link. In otherinstances, the peripheral processing devices can be operatively coupledto the edge devices via intermediate nodes. Such a connection can besaid to be a multiple physical hop link.

In some embodiments, the edge devices of the edge device network 145 canbe configured to provide services (e.g., to customers) such as, forexample, VPN (virtual private network), pseudowire, Internet access,and/or the like. The edge devices can be upgraded, configured, rebootedor shut down for maintenance when, for example, new customers join theswitch fabric system 100, new services are initiated, new edge devicesare introduced to accommodate new customers, and/or the like.Additionally, in some embodiments, an edge device can be referred to as,for example, a label edge, PE router, provider edge node, etc.

FIG. 2 is a block diagram of an edge device 200, according to anembodiment. The edge device 200 can be structurally and functionallysimilar to the edge devices 150, 162, 164, 170, 180 shown and describedwith respect to FIG. 1. Particularly, similar to the edge devices of theedge device network 145 in FIG. 1, the edge device 200 can be any deviceconfigured to be coupled to one or more switch fabric devices of aswitch fabric (e.g., the switch fabric devices 110, 120, 130, 140 of theswitch fabric 105 in FIG. 1). Thus, the edge device 200 can beoperatively coupled to one or more other edge devices via the switchfabric.

As shown in FIG. 2, the edge device 200 includes a communicationsinterface 230, a memory 210, and a processor 220 that includes a tunnelmodule 225. Although not shown in FIG. 2, the edge device 200 caninclude other modules with various functions. For example, the edgedevice 200 can include a DHCP module configured to obtain an address(according to DHCP) from the switch fabric device that operativelycouples the edge device 200 to the switch fabric. For another example,the edge device 200 can include an ARP module configured to communicatewith the switch fabric device that operatively couples the edge device200 to the switch fabric according to ARP.

Each operation(s) of the communications interface 230 (e.g.,transmit/receive data), the tunnel module 225 (e.g.,encapsulate/decapsulate data units), other modules (not shown in FIG. 2)of the edge device 200, as well as operation(s) on the memory 210, canbe controlled by the processor 220. The processor 220 can be anysuitable processor configured to run and/or execute the module(s)included in the processor 220. Each module in the processor 220 can beany combination of hardware-based module (e.g., a field-programmablegate array (FPGA), an application specific integrated circuit (ASIC), adigital signal processor (DSP), etc.) and/or software-based module(e.g., a module of computer code stored in the memory 210 and/orexecuted at the processor 220) capable of performing one or morespecific functions associated with that module.

The tunnel module 225 can be configured to enable the edge device 200 totransmit data to and receive data from other edge devices coupled to theswitch fabric using a tunnel though the switch fabric. In someembodiments, as described in detail below, the tunnel module 225 can beconfigured to enable the edge device 200 to communicate with other edgedevices using a MPLS tunnel through the switch fabric. Specifically, thetunnel module 225 can be configured to encapsulate data with a labelstack associated with the MPLS tunnel. As described in detail below,such a label stack can include one or more labels such as a labelidentifying a MPLS tunnel connecting two switch fabric devices in theswitch fabric, a label identifying a route from a switch fabric deviceto an edge device coupled to that switch fabric device, and/or the like.

The communications interface 230 of the edge device 200 can include, forexample, one or more ports (not shown in FIG. 2) that can be used toimplement connection(s) (e.g., wired connection, wireless connection)between the edge device 200 and the switch fabric device(s) thatoperatively couple the edge device 200 to the switch fabric. Theconnection(s) can be, for example, twisted-pair electrical signaling viaelectrical cables, fiber-optic signaling via fiber-optic cables, and/orthe like. As such, the edge device 200 can be configured to receive dataand/or send data through the port(s) of the communications interface230, which are connected with the communications interfaces of theswitch fabric device(s). Furthermore, in some embodiments, the edgedevice 200 can implement one type of connection with one of the switchfabric devices (e.g., the switch fabric device 110 in FIG. 1) throughone port of the communications interface 230, while implementing adifferent type of connection with another switch fabric device (e.g.,the switch fabric device 130 in FIG. 1) through another port of thecommunications interface 230.

In some embodiments, the memory 210 can be, for example, a random-accessmemory (RAM) (e.g., a dynamic RAM, a static RAM), a flash memory, aremovable memory, and/or so forth. The control information associatedwith interacting with the switch fabric device(s) that operativelycouple the edge device 200 to the switch fabric and establishing MPLStunnels with other edge devices through the switch fabric can be storedin the memory 210. For example, as discussed below, an address assignedto the edge device 200 and/or a label identifying a route from a switchfabric device (i.e., the switch fabric device that couples the edgedevice 200 to the switch fabric) to the edge device can be stored in thememory 210. For another example, labels identifying routes to other edgedevices, and/or labels identifying MPLS tunnels within the switch fabriccan also be stored in the memory 210.

Returning to FIG. 1, each switch fabric device (e.g., the switch fabricdevice 110, 120, 130, 140) of the switch fabric 105 can be any deviceconfigured to be operatively coupled to other switch fabric device(s)and/or edge device(s) (e.g., the edge devices 150, 162, 164, 170, 180)such that the switch fabric 105 can operatively couple the edge deviceswith each other and enable data transmission among the edge devices.Thus, the switch fabric devices of the switch fabric 105 can beconfigured to offer connectivity among the edge devices and to othernetworks (not shown in FIG. 1). Such a switch fabric device can be, forexample, a routing device (e.g., a L2/L3 router), switching device(e.g., a L2/L3 switch), gateway, workstation, server, compute node,and/or the like. In some embodiments, a switch fabric device can bereferred to as, for example, a core node, label switch, provider node,provider router, fabric node, etc.

In some embodiments, the switch fabric devices of the switch fabric 105do not offer services other than providing connectivity to the edgedevices. In such embodiments, maintenance of a switch fabric device isperformed when a hardware or software failure occurs at the switchfabric device, a new line card is to be installed at the switch fabricdevice, and/or the like. As discussed in detail below, because of theseparated administration and operation between the edge device network145 and the switch fabric 105, the switch fabric devices are notdisturbed when an edge device is modified.

FIG. 3 is a system block diagram of a switch fabric device 300,according to an embodiment. The switch fabric device 300 can bestructurally and functionally similar to the switch fabric devices 110,120, 130, 140 shown and described with respect to FIG. 1. Particularly,similar to the switch fabric devices of the switch fabric 105 in FIG. 1,the switch fabric device 300 can be included within a switch fabric(e.g., the switch fabric 105 in FIG. 1), and configured to operativelycouple one or more edge devices (e.g., the edge devices 150, 162, 164,170, 180 in FIG. 1) to that switch fabric.

As shown in FIG. 3, the switch fabric device 200 includes acommunications interface 360, a memory 320 that includes a routing table325, and a processor 340 that includes a tunnel module 345. Although notshown in FIG. 3, the switch fabric device 300 can include other moduleswith various functions. For example, the switch fabric device 300 caninclude a DHCP module configured to handle DHCP requests received fromthe edge device(s) coupled to the switch fabric device 300. For anotherexample, the switch fabric device 300 can include an ARP moduleconfigured to communicate with the edge device(s) that are coupled tothe switch fabric device 300 according to ARP.

Each operation(s) of the communications interface 360 (e.g.,transmit/receive data), the tunnel module 345 (e.g., transmittedtunneled data), other modules (not shown in FIG. 3) of the switch fabricdevice 300, as well as operation(s) on the memory 320 (e.g.,manipulation on the routing table 325), can be controlled by theprocessor 340. The processor 340 can be any suitable processorconfigured to run and/or execute the module(s) included in the processor340. Each module in the processor 340 can be a hardware-based module(e.g., a CPU, a general purpose processor, a FPGA, an ASIC, a DSP,etc.), a software-based module (e.g., a module of computer code storedin the memory 320 and/or executed at the processor 340), and/or acombination of hardware and software-based modules that is capable ofperforming one or more specific functions associated with that module.

The tunnel module 345 can be configured to enable the switch fabricdevice 300 to transmit tunneled data to and receive tunneled data fromother switch fabric devices or edge device(s) coupled to the switchfabric device 300. Particularly, as described in detail below, thetunnel module 345 can be configured to enable transmission of tunneleddata using MPLS tunnels that connect the switch fabric device 300 withother switch fabric devices of the switch fabric. Thus, edge device(s)coupled to the switch fabric device 300 can communicate with other edgedevices coupled to the switch fabric using the MPLS tunnels through theswitch fabric device 300. The tunnel module 345 can also be configuredto decapsulate data to retrieve label(s) included in the data, anddetermine a route to transmit the decapsulate data based on theretrieved label(s). In some embodiments, the tunnel module 345 can beconfigured to determine a route (e.g., a MPLS tunnel) for tunneled databased on routing information stored in the routing table 325.

The communications interface 360 of the switch fabric device 300 caninclude, for example, at least two ports (not shown in FIG. 3) that canbe used to implement connections between the switch fabric device 300and the edge device(s), and between the switch fabric device 300 andother switch fabric device(s) of the switch fabric. The connections canbe, for example, twisted-pair electrical signaling via electricalcables, fiber-optic signaling via fiber-optic cables, and/or the like.As such, the switch fabric device 300 can be configured to receive dataand/or send data through the ports of the communications interface 360,which are connected with the communications interfaces of the edgedevice(s) and the other switch fabric device(s). Furthermore, in someembodiments, the switch fabric device 300 can implement one type ofconnection with one of the edge device(s) and other switch fabricdevice(s) through one port of the communications interface 360, whileimplementing a different type of connection with another edge device orswitch fabric device through another port of the communicationsinterface 360. For example, the switch fabric device 300 can implement atwisted-pair electrical signaling connection (e.g., via an electricalcable) with an edge device and implement a fiber-optic signalingconnection (e.g., via a fiber-optic cable) with another switch fabricdevice.

In some embodiments, the memory 320 can be, for example, a RAM (e.g., adynamic RAM, a static RAM), a flash memory, a removable memory, and/orso forth. The control information associated with interacting with theedge device(s) that are coupled to the switch fabric device 300 can bestored in the memory 320. In some embodiments, routing informationassociated with tunneling data with other switch fabric device(s) can bestored in the routing table 325. In some embodiments, for example, therouting table can be configured to store a label forwarding informationbase (LFIB) that includes routing information associated with labels forthe MPLS tunnels and/or the edge devices of the edge device network.

For example, a LFIB in the routing table 325 can store an entryincluding a label identifying a MPLS tunnel connecting the switch fabricdevice 300 with another switch fabric device, and an identifier of aport of the switch fabric device 300 (included in the communicationsinterface 360) associated with the MPLS tunnel. Thus, in response toreceiving data unit(s) including the label identifying the MPLS tunnel,the tunnel module 345 can determine the port based on the label and theentry stored in the LFIB in the routing table 325. The tunnel module 345can then send the data unit(s) via the port, such that the data unit(s)is sent to the other switch fabric device through the MPLS tunnel.

For another example, a LFIB in the routing table 325 can store an entryincluding a label identifying an edge device coupled to the switchfabric device 300, and an identifier of a port of the switch fabricdevice 300 (included in the communications interface 360) associatedwith the edge device. Thus, in response to receiving data unit(s)including the label identifying the edge device, the tunnel module 345can determine the port based on the label and the entry stored in theLFIB in the routing table 325. The tunnel module 345 can then send thedata unit(s) via the port, such that the data unit(s) is sent to theedge device.

Returning to FIG. 1, in some embodiments, the edge device network 145and the switch fabric 105 can be separately administrated, controlledand/or operated. That is, the switch fabric system 100 can implementseparated administration, control and/or operation for the edge devices(e.g., the edge devices 150, 162, 164, 170, 180) of the edge devicenetwork 145 and for the switch fabric devices (e.g., the switch fabricdevices, 110, 120, 130, 140) of the switch fabric. In such embodiments,the separation between the edge devices and the switch fabric devicescan be implemented in one or more aspects including, for example,administrative separation, control plane separation, data planeseparation, address separation, and/or the like.

In some embodiments, administrative separation can be implementedbetween the edge devices of the edge device network 145 and the switchfabric devices of the switch fabric 105. Specifically, the edge devicesand the switch fabric devices can be administrated by two (independent)groups of administrators separately. For example, the edge devicenetwork 145 can be administrated by a group of one or more edgeadministrators, and the switch fabric 105 can be administrated byanother group of one or more fabric administrators. Each edgeadministrator or fabric administrator can be, for example, a person, amachine (automatically executed or manually operated by a person), or acombination of person(s) and machine(s) that performs the administratingfunction for the edge device(s) or the switch fabric device(s).

As a result of the administrative separation, no coordination isrequired from one side of the edge device network 145 or the switchfabric 105 when the other side of the edge device network 145 or theswitch fabric 105 is being administrated (e.g., modified, configured).For example, the fabric administrator(s) can administrate (e.g., reboot,upgrade, modify configuration, change MPLS protocol setting, etc.) aswitch fabric device (e.g., the switch fabric device 110, 120, 130 or140) of the switch fabric 105 without coordination from the edgeadministrator(s) and without disruption, modification or reconfigurationto any edge device of the edge device network 145. For another example,similarly, the edge administrator(s) can administrate (e.g., reboot,upgrade, modify configuration, etc.) an edge device (e.g., the edgedevice 150, 162, 164, 170 or 180) of the edge device network 145 withoutcoordination from the fabric administrator(s) and without disruption,modification or reconfiguration to any switch fabric device of theswitch fabric 105.

Furthermore, as a result of administrative separation and/or otherseparation mechanisms, plug-and-play connectivity can be implemented forthe edge device network 145 and the switch fabric 105. That is, the edgeadministrator(s) can add, remove or move edge devices withoutcoordination with the fabric administrator(s) and without disruption,modification or reconfiguration to the edge devices. Similarly, thefabric administrator(s) can add, remove or move edge devices withoutcoordination with the fabric administrator(s) and without disruption,modification or reconfiguration to the switch fabric devices.

In some embodiments, routing protocol separation can be implementedbetween the edge devices of the edge device network 145 and the switchfabric devices of the switch fabric 105. Specifically, the routingprotocol implemented within the switch fabric 105 can be performed(e.g., exchange of signals, messages, etc.) without coordination of theedge device network. Furthermore, the protocol (e.g., DHCP, ARP)implemented between the edge devices and the switch fabric devices canbe performed (e.g., exchange of signals, messages, etc.) withoutcoordination between the edge administrator(s) and the fabricadministrator(s). As a result, the protocols implemented in the switchfabric system 100 can be performed and managed without administrativecoordination between the fabric administrator(s) and the edgeadministrator(s).

In some embodiments, as shown in FIG. 1, multiple edge devices (e.g.,the edge devices 162, 164) can be coupled to one switch fabric device(e.g., the switch fabric device 130). In some embodiments, as shown inFIG. 1, an effective multi-homing mechanism can be implemented for theedge devices of the edge device network 145. Specifically, an edgedevice can be coupled and multi-homed to more than one switch fabricdevice. In such embodiments, the multiple links between the edge deviceand the associated switch fabric devices can be used for load balancingtraffic transmitted between the edge device and the switch fabric 105.As a result, the traffic within the switch fabric 105 can be loadbalanced as well. Furthermore, the multiple links between the edgedevice and the associated switch fabric devices can be used to improveresilience for the connection between the edge device and the switchfabric 105. As a result, fast restoration can be achieved for datatransmission between the edge device and the switch fabric 105.Specifically, the failover time upon detection of a failure (e.g., afailure at a link connecting the edge device and an associated switchfabric device, a failure at an associated switch fabric device coupledto the edge device) can be reduced by directing data traffic to theremaining link(s) that connect the edge device and the switch fabric105.

For example, as shown in FIG. 1, the edge device 164 can be coupled, viatwo separate links respectively, to the switch fabric devices 110 and130. As a result, data traffic transmitted between the edge device 164and the switch fabric devices 110, 130 can be load balanced between thetwo links. Furthermore, data traffic within the switch fabric 105 thatis transmitted to or from the switch fabric devices 110, 130 can be loadbalanced based on the load on the two links. Additionally, the two linkscan be used to improve resilience and provide fast restoration for theedge device 164.

In some embodiments, connectivity isolation can be implemented betweenthe edge devices of the edge device network 145 and the switch fabricdevices of the switch fabric 105. Specifically, each edge device fromthe edge device network 145 does not communicate directly with eachremaining edge device from the edge device network 145. Instead, theedge devices of the edge device network 145 communicate with each otherthrough the switch fabric 105. That is, each edge device from the edgedevice network 145 can send data unit(s) (e.g., data-plane data unit(s),control-plane data unit(s)) to each remaining edge device from the edgedevice network 145 via one or more switch fabric devices of the switchfabric 105, but not directly from one edge device to another edgedevice. Furthermore, the data unit(s) (e.g., data-plane data unit(s),control-plane data unit(s)) that can be transmitted between the edgedevices and the switch fabric devices is restricted. For example, dataunit(s) can be transmitted between the edge devices and the switchfabric devices according to a set of given protocols. In other words,data unit(s) is not transmitted between the edge devices and the switchfabric devices according to any protocol not included in the set ofgiven protocols. In some instances, for example, the switch fabric 105can provide MPLS connectivity (e.g., via MPLS tunnels) to the edgedevices of the edge device network 145 without providing Internetprotocol (IP) connectivity to those edge devices. Thus, data unit(s) canbe transmitted between the edge devices and the switch fabric devicesaccording to an MPLS protocol, but not according to an IP routingprotocol. As a result of connectivity isolation, a compromised edgedevice is not enabled to attack the switch fabric 105. Similarly, acompromised switch fabric device is not enabled to attack the edgedevice network 145.

In some embodiments, address separation (or address independence) can beimplemented between the edge devices of the edge device network 145 andthe switch fabric devices of the switch fabric 105. Specifically, theedge device network 145 and the switch fabric 105 can use twoindependent address domains, respectively. In some instances, the twoaddress domains can have overlapping address(es) but without conflict ofthe overlapping address(es). In some instances, the two address domainscan be completely different (i.e., sharing no overlapping address).

In some embodiments, an edge device of the edge device network 145 canbe configured to obtain an address, according to an auto-discoveryprotocol (e.g., DHCP, ARP), from a switch fabric device coupled to thatedge device. In such embodiments, for example, an edge administratorresponsible for administrating the edge device network 145 can select anaddress space (e.g., an address domain) for the edge device network 145and then notify a fabric administrator responsible for administratingthe switch fabric 105 of the selected address space. Furthermore, theedge administrator can also update any change on the address space forthe edge device network 145 to the fabric administrator. As a result,the fabric administrator can assign an address space, which is notoverlapping with the address space for the edge device network 145, tothe switch fabric devices of the switch fabric 105. Thus, the addressesassigned to the edge devices can be different from the addressesassigned to the switch fabric devices.

For example, the edge device 162 can send a request for address (e.g., aDHCP request, an ARP request) to the switch fabric device 130. Inresponse to the request, an address is selected from an address spacefor the edge device network 145 at the switch fabric device 130 and thensent from the switch fabric device 130 to the edge device 162. In someinstances, the address assigned to the edge device 162 can be alsoincluded in an address space for the switch fabric 105. Thus, thataddress will not be assigned to any switch fabric device of the switchfabric 105; as a result no switch fabric device shares the identicaladdress with the edge device 162.

In some embodiments, the switch fabric devices (e.g., the switch fabricdevices 110, 120, 130, 140) of the switch fabric 105 can be collectivelyconfigured to enable data transmission between the edge devices (e.g.,the edge devices 150, 162, 164, 170, 180) of the edge device network145. The switch fabric 105 can be configured to implement a mesh oflabel-switched paths (LSPs) such that the switch fabric devices of theswitch fabric 105 can transmit data with each other using the mesh ofLSPs. The mesh of LSPs can be implemented using MPLS tunnels thatconnect the switch fabric devices, thus to form a mesh of MPLS tunnels.In some embodiments, routing protocols such as, for example, IGP, LDP,RSVP-TE, etc., can be used to generate the mesh of MPLS tunnels.Specifically, the mesh of MPLS tunnels can be established by executing,for example, LGP with LDP, RSVP-TE, and/or other routing protocol withinthe switch fabric 105.

In some embodiments, the mesh of MPLS tunnels is implemented within theswitch fabric 105 and not extended to the edge devices of the edgedevice network 145. That is, the routing protocol(s) implemented withinthe switch fabric 105 are not implemented at the connections between theswitch fabric devices and the edge devices. Instead, an auto-discoveryprotocol (e.g., DHCP, ARP, LLDP) can be used to enable communicationbetween the switch fabric devices and the edge devices. Details ofenabling data transmission between edge devices using MPLS tunnels arefurther described below.

As discussed above, the switch fabric 105 and the edge device network145 each can have an independent address space. In such instances, eachswitch fabric device of the switch fabric 105 can be allocated a blockof addresses (e.g., IP addresses) from the address space for the edgedevice network 145. Thus, a switch fabric device can assign an addressfrom the block of addresses allocated to that switch fabric device to anedge device in response to receiving a request (e.g., a DHCP request, anARP request) from that edge device. Furthermore, in some embodiments,the switch fabric devices of the switch fabric 105 can maintain IPconnectivity among themselves without offering IP connectivity to theedge devices of the edge device network 145.

A method of initializing data transmission between an edge device (e.g.,the edge device 162) and other edge devices (e.g., the edge devices 164,170, 180) using MPLS tunnels through the switch fabric 105 can beconsidered in reference to FIG. 1. Initially, the edge device 162 cansend a request (shown as signal 192 in FIG. 1) to the switch fabricdevice 130 according to an auto-discovery protocol (e.g., DHCP, ARP,LLDP). In some embodiments, the edge device 162 can be configured tosend such a request in response to, for example, the edge device 162being booted up, turned on, coupled to the switch fabric device 130,and/or the like.

In some embodiments, the request can be a request for an address and/ora label assigned to the edge device 162. For example, the request can bea DHCP request for an IP address assigned to the edge device 162 and/ora label for other edge devices to send data to the edge device 162. Inresponse to the request, the switch fabric device 130 can send aresponse (shown as signal 194 in FIG. 1) to the edge device 162. Theresponse can include an address (e.g., IP address) assigned to the edgedevice 162. For example, the switch fabric device 130 can assign an IPaddress 10.1.3.1 to the edge device 162. As discussed above, the addressassigned to the edge device 162 can be selected from an address spacefor the edge device network 145 that is independent of an address spacefor the switch fabric 105. In some embodiments, the address space forthe edge device 145 can overlap with the address space for the switchfabric 105. As a result, the address assigned to the edge device 162 cancorrespond to an address included in (but not yet assigned from) theaddress space for the switch fabric 105. In such embodiments, theaddress assigned to the edge device 162 can be selected such that thataddress is not assigned to any switch fabric device of the switch fabric105.

In some embodiments, in response to the request, the switch fabricdevice 130 can define a label for the edge device 162 such that thelabel can be used to route data to the edge device 162. For example, theswitch fabric device 130 can define a label [EL162→162 via 130], whichindicates that the edge device 162 can be reached via the switch fabricdevice 130. In some embodiments, the address assigned to the edge device162 can be included in the label defined for the edge device 162. Insuch embodiments, the label can be, for example, [EL162→10.1.3.1 via130]. The switch fabric device 130 can then be configured to store thelabel for the edge device 162 in, for example, a routing table in theswitch fabric device 130 (e.g., the routing table 325 in the switchfabric device 300 in FIG. 3). In some embodiments, the label for theedge device 162 can be added to, for example, a LFIB in the routingtable. The label in the LFIB can be associated with and used to identifya port of the switch fabric device 130 that connects the switch fabricdevice 130 to the edge device 162.

In some embodiments, the switch fabric device 130 can be configured tosend the label (together with the assigned address) to the edge device162 (e.g., via the signal 194). In some embodiments, upon assigning theaddress and defining the label for the edge device 162, the switchfabric device 130 can be configured to announce the address and thelabel to other edge devices (e.g., the edge devices 150, 164, 170, 180)of the edge device network 145 that are coupled to the switch fabric105, and/or to other switch fabric devices of the switch fabric 105.Specifically, the switch fabric device 130 can be configured to send anadvertisement (e.g., message) including routing information for the edgedevice 162 (e.g., the address of the edge device 162, the label of theedge device 162, and an identifier of the switch fabric device 130 asthe “next-hop” to reach the edge device 162) to the other edge devicesvia the switch fabric devices of the switch fabric 105. For example, theadvertisement can include routing information such as 10.1.3.1, EL162,next-hop: 130. As a result, information associated with routing to theedge device 162 (including the address, label, and next-hop of the edgedevice 162) is made available at the other switch fabric devices of theswitch fabric 105 and/or the other edge devices of the edge devicenetwork 145.

In some embodiments, as an alternative to the switch fabric device 130sending the routing information of the edge device 162 to other edgedevices, the edge device 162 can be configured to send its routinginformation to other edge devices of the edge device network 145. Insuch embodiments, the edge device 162 can send the routing information(e.g., including the address of the edge device 162, the label of theedge device 162, and an identifier of the switch fabric device 130 asthe “next-hop” to reach the edge device 162) to the other edge devicesaccording to a network-address-based protocol such as, for example, BGP.In some embodiments, the BGP messages can be sent within a control plane(not shown) of the edge device network 145 that is separate from thecontrol plane of the switch fabric 105 (i.e., not via the switch fabric105). In such embodiments, for example, the edge device 162 can send aBGP message including the routing information to the edge device 180without going through the switch fabric 105 (shown as signal 199 in FIG.1). In other embodiments, the BGP messages can be sent through thecontrol plane of the switch fabric 105 (i.e., via the switch fabric105). In such embodiments, for example, the edge device 162 can send aBGP message including the routing information to the edge device 180 viathe switch fabric devices 130, 140 (not shown in FIG. 1).

As an example illustrated in FIG. 1, when the edge device 180 attemptsto communicate with the edge device 162, the edge device 180 can firstdetermine the switch fabric device 130 as the next-hop to reach the edgedevice 162 based on received routing information of the edge device 162.The edge device 180 can then send a request (shown as signal 193 inFIG. 1) to the switch fabric device 140. The request can be, forexample, an ARP request to resolve a route to the switch fabric device130. In response to the ARP request, the switch fabric device 140 cancheck to determine if MPLS connectivity (e.g., a MPLS tunnel) existsbetween the switch fabric device 140 and the switch fabric device 130.After determining that a MPLS tunnel (e.g., MPLS tunnel 190 in FIG. 1)exists between the switch fabric device 140 and the switch fabric device130, the switch fabric device 140 can define a label for that MPLStunnel. For example, the switch fabric device 140 can define a label[FL140-130: 140 to 130] for the MPLS tunnel 190. The switch fabricdevice 140 can then add the label to, for example, a LFIB in a routingtable of the switch fabric device 140. The label in the LFIB can beassociated with and used to identify a port of the switch fabric device140 that connects the switch fabric device 140 to the switch fabricdevice 130 via the MPLS tunnel 190.

After defining the label for the MPLS tunnel 190, the switch fabricdevice 140 can send the label to the edge device 180 (shown as signal195 in FIG. 1). In some embodiments, the switch fabric device 140 cansend to the edge device 180, for example, an entropy label of the switchfabric device 130 and/or entropy label(s) of other switch fabricdevice(s). Such an entropy label can include, for example, loadbalancing information associated with the MPLS tunnel 190 (e.g., withrespect to load balancing information of other MPLS tunnel(s) within theswitch fabric 105). In some embodiments, the switch fabric device 140can send to the edge device 180 other metric value(s) associated withthe switch fabric device 130, the switch fabric device 140, and/or otherswitch fabric device(s). Thus, the edge device 180 can decide whether tocommunicate with the edge device 162 via the switch fabric devices 140and 130 or any other alternative route (not shown in FIG. 1) through theswitch fabric 105 based on the entropy label(s) and/or other metricvalue(s) associated with the switch fabric device 130, the switch fabricdevice 140, and/or other switch fabric device(s).

After receiving the label for the MPLS tunnel 190 and/or additionalinformation, the edge device 180 can use a label stack <FL140-130,EL162> to establish a MPLS connection with the edge device 162. Forexample, the edge device 180 can send a data unit (e.g., a data packet,a data cell, a data frame) to the edge device 162 through the switchfabric device 140, the MPLS tunnel 190, and the switch fabric device130. Specifically, a tunnel module of the edge device 180 (e.g., thetunnel module 225 of the edge device 200 in FIG. 2) can encapsulate thedata unit with the label stack <FL140-130, EL162>. First, the labelEL162 can be used at the tunnel module of the edge device 180 toencapsulate the data unit to define a first encapsulation of the dataunit. Next, the label FL140-130 can be used at the tunnel module of theedge device 180 to encapsulate the first encapsulation of the data unitto define a second encapsulation of the data unit. The edge device 180can then send the second encapsulation of the data unit, as theencapsulated data, to the switch fabric device 140.

Upon receiving the data unit encapsulated with the label stack<FL140-130> (i.e., the second encapsulation of the data unit), a tunnelmodule of the switch fabric device 140 (e.g., the tunnel module 345 ofthe switch fabric device 300 in FIG. 3) can decapsulate the labelFL140-130 from the second encapsulation of the data unit to retrieve thefirst encapsulation of the data unit. Based on the label FL140-130, theswitch fabric device 140 can determine to send the decapsulated data(i.e., the first encapsulation of the data unit) to the switch fabricdevice 130 via the MPLS tunnel 190. For example, the switch fabricdevice 140 can determine a port to send the first encapsulation of thedata unit based on that an identifier of the port is associated with thelabel FL140-130 in the routing table of the switch fabric device 140.

Upon receiving the data unit encapsulated with the label EL162 (i.e.,the first encapsulation of the data unit), a tunnel module of the switchfabric device 130 (e.g., the tunnel module 345 of the switch fabricdevice 300 in FIG. 3) can decapsulate the label EL162 from the firstencapsulation of the data unit to retrieve the original data unit. Basedon the label EL162, the switch fabric device 130 can determine to sendthe data unit to the edge device 162. For example, the switch fabricdevice 130 can determine a port to send the data unit based on that anidentifier of the port is associated with the label EL162 in the routingtable of the switch fabric device 130. Thus, the edge device 180 cansend the data unit to the edge device 162 via an MPLS tunnel through theswitch fabric 105.

As another example illustrated in FIG. 1, when the edge device 164attempts to communicate with the edge device 162, the edge device 164can first determine the switch fabric device 130 as the next-hop toreach the edge device 162 based on received routing information of theedge device 162. In some embodiments, similar to the edge device 180described above, the edge device 164 can send an ARP request (shown assignal 196 in FIG. 1) to the switch fabric device 130, to resolve aroute to the switch fabric device 130. In response to the ARP request,the switch fabric device 130 can return a response (shown as signal 198in FIG. 1) including, for example, a null label to the edge device 164.Such a null label indicates that an MPLS tunnel between switch fabricdevices is not used to reach the switch fabric device 130 from theswitch fabric device 130. The edge device 164 can then encapsulate adata unit (e.g., a data packet, a data cell, a data frame) intended forthe edge device 162 using a label stack <null label, EL162> in a methodsimilar to that of the edge device 180 described above. The edge device164 can then send the encapsulated data unit to the edge device 162 viathe switch fabric device 130 in a method similar to that of the edgedevice 180 described above. In some other embodiments, the step ofsending an ARP request to resolve a route to the switch fabric device130 can be avoided or skipped if the edge device 164 determines that itis directly coupled to the switch fabric device 130 (as the next-hop toreach the edge device 162). In such embodiments, the edge device 164 canencapsulate data intended for the edge device 162 using the label EL162,and then send the encapsulated data to the switch fabric device 130.Upon receiving the encapsulated data (e.g., encapsulated using the labelstack <null label, EL162> or the label EL162) from the edge device 164,the tunnel module of the switch fabric device 130 can decapsulate theencapsulated data to retrieve the original data intended for the edgedevice 162, and then send the data to the edge device 162.

FIG. 4 is a flow chart illustrating a method 400 for communicationbetween edge devices via a switch fabric, according to an embodiment.The method 400 can be executed at a first edge device that isstructurally and functionally similar to the edge devices (e.g., theedge devices 150, 162, 164, 170, 180, 200) shown and described withrespect to FIGS. 1 and 2. Particularly, the first edge device can becoupled to a switch fabric device of a switch fabric (e.g., the switchfabric device 110, 120, 130 or 140 of the switch fabric 105 in FIG. 1,the switch fabric 300 in FIG. 3). The switch fabric device isoperatively coupled to a second edge device (e.g., via other switchfabric device(s) of the switch fabric).

In some embodiments, similar to the edge device 200 shown and describedwith respect to FIG. 2, the first edge device can include a processor(e.g., the processor 220) and a memory (e.g., the memory 210). Thememory can be, for example, a non-transitory processor-readable medium.The code representing instructions to perform the method 400 can bestored in the non-transitory processor-readable medium included in thefirst edge device, and executed by the processor of the first edgedevice. The code includes code to be executed by the processor to causethe first edge device to operate the functions illustrated in FIG. 4 anddescribed as follows.

At 402, the first edge device can send, at a first time, a requestaccording to an auto-discovery protocol to the switch fabric device ofthe switch fabric. As discussed above, the auto-discovery protocol canbe, for example, DHCP. The request (e.g., DHCP request) can be a requestfor an address to be assigned to the first edge device, and/or a labelto be defined for the first edge device (e.g., the label EL162 in theexample described above with respect to FIG. 1). The label can be usedby other edge devices and/or switch fabric devices to route data to thefirst edge device.

At 404, the first edge device can receive, at a second time after thefirst time and in response to the request, a response from the switchfabric device according to the auto-discovery protocol. For example, thefirst edge device can receive a DHCP response from the switch fabricdevice, which includes an IP address assigned to the first edge device.In some embodiments, the response can include the label defined for thefirst edge device. In some embodiments, the response can include otherrouting information associated with routing data to the first edgedevice.

At 406, the first edge device can send to the second edge device amessage or signal including the label, which is included in theresponse, such that an MPLS tunnel is established with the second edgedevice based on the label. As discussed above, the first edge device cansend the label to the second edge device using, for example, a BGPmessage. Alternatively, the switch fabric device can send advertisements(e.g., in message(s) or signal(s)) including the label to other switchfabric devices of the switch fabric, which can then in turn send thelabel to the other edge devices including the second edge device.

After receiving the label, the second edge device can initiateestablishing an MPLS tunnel to reach the first edge device, as describedin detail above. Specifically, the second edge device can determine thenext-hop switch fabric device (the switch fabric device in this example)for the first edge device based on the label. The second edge device canthen send an ARP request to an associated switch fabric device (i.e.,the switch fabric device that operatively couples the second edge deviceto the switch fabric), to resolve a route to the next-hop switch fabricdevice. In response to the ARP request, the second edge device canreceive a label identifying a MPLS tunnel (e.g., the label FL140-130 inthe example described above with respect to FIG. 1) connecting theswitch fabric device associated with the second edge device and theswitch fabric device associated with the first edge device (e.g., theMPLS tunnel 190 connecting the switch fabric device 140 and the switchfabric device 130 in FIG. 1).

At 408, the second edge device can send a data unit using the labelstack that includes the label for the first edge device and the labelfor the MPLS tunnel. Based on the label stack, the data can unit betransmitted to the first edge device through the switch fabric deviceassociated with the second edge device, the MPLS tunnel, and the switchfabric device associated with the first edge device, in that order.Specifically, the label for the MPLS tunnel (e.g., FL140-130) can beused, at the switch fabric device associated with the second edgedevice, to route the data unit from the switch fabric device associatedwith the second edge device to the switch fabric device associated withthe first edge device. The label for the first edge device (e.g., EL162)can be used, at the switch fabric device associated with the first edgedevice, to route the data unit from the switch fabric device associatedwith the first edge device to the first edge. As a result of the secondedge device sending the data unit to the first edge device using theMPLS tunnel, the first edge device can receive the data unit from thesecond edge device through the MPLS tunnel at a third time after thesecond time.

While shown and described herein with respect to FIG. 1 that the edgedevices of an edge device network interact with switch fabric devices ofa switch fabric to obtain routing information (e.g., labels identifyingMPLS tunnels and other edge devices) associated with communicating withother edge devices, in other embodiments, one or more route reflectorscan provide routing information to the edge devices of the edge devicenetwork. Such a route reflector can be implemented at an edge device, aswitch fabric device, or a device separate from the edge device networkand the switch fabric. For example, a route reflector can be configuredto receive, from an edge device, BGP messages including updated routinginformation of that edge device. The route reflector can be configuredto forward the BGP messages to other edge devices. Thus, each edgedevice of the edge device network maintains a BGP connection with theroute reflector, and does not maintain any connection with other edgedevices. For another example, a route reflector can function as a DHCPserver and/or an ARP server for the edge device network. Thus, eachswitch fabric device can forward the DHCP requests and/or ARP requestsreceived from their associated edge devices to the route reflector(e.g., via other switch fabric devices of the switch fabric), andreceive DHCP responses and/or ARP responses from the route reflector.For yet another example, a route reflector can function as a centralizedcontroller that stores routing information associated with the switchfabric and provides the routing information to the switch fabric devicesof the switch fabric. Thus, each switch fabric device communicates withthe route reflector to obtain labels for the MPLS tunnels and/or theedge devices. The switch fabric devices can then use the labels receivedfrom the route reflector to route data through the switch fabric.

Some embodiments described herein relate to a computer storage productwith a non-transitory computer-readable medium (also can be referred toas a non-transitory processor-readable medium) having instructions orcomputer code thereon for performing various computer-implementedoperations. The computer-readable medium (or processor-readable medium)is non-transitory in the sense that it does not include transitorypropagating signals per se (e.g., a propagating electromagnetic wavecarrying information on a transmission medium such as space or a cable).The media and computer code (also can be referred to as code) may bethose designed and constructed for the specific purpose or purposes.Examples of non-transitory computer-readable media include, but are notlimited to: magnetic storage media such as hard disks, floppy disks, andmagnetic tape; optical storage media such as Compact Disc/Digital VideoDiscs (CD/DVDs), Compact Disc-Read Only Memories (CD-ROMs), andholographic devices; magneto-optical storage media such as opticaldisks; carrier wave signal processing modules; and hardware devices thatare specially configured to store and execute program code, such asApplication-Specific Integrated Circuits (ASICs), Programmable LogicDevices (PLDs), Read-Only Memory (ROM) and Random-Access Memory (RAM)devices. Other embodiments described herein relate to a computer programproduct, which can include, for example, the instructions and/orcomputer code discussed herein.

Examples of computer code include, but are not limited to, micro-code ormicro-instructions, machine instructions, such as produced by acompiler, code used to produce a web service, and files containinghigher-level instructions that are executed by a computer using aninterpreter. For example, embodiments may be implemented usingimperative programming languages (e.g., C, Fortran, etc.), functionalprogramming languages (Haskell, Erlang, etc.), logical programminglanguages (e.g., Prolog), object-oriented programming languages (e.g.,Java, C++, etc.) or other suitable programming languages and/ordevelopment tools. Additional examples of computer code include, but arenot limited to, control signals, encrypted code, and compressed code.

While various embodiments have been described above, it should beunderstood that they have been presented by way of example only, and notlimitation. Where methods described above indicate certain eventsoccurring in certain order, the ordering of certain events may bemodified. Additionally, certain of the events may be performedconcurrently in a parallel process when possible, as well as performedsequentially as described above.

What is claimed is:
 1. A method, comprising: operatively coupling a nodewithin a switch fabric separate from an edge device network such thatthe node of the switch fabric can be administrated without disruption,modification, or reconfiguration of edge devices of the edge devicenetwork; operatively coupling to an edge device via the switch fabric soas to form the edge device network to facilitate communication with theedge device via a multiprotocol label switching (MPLS) tunnel throughthe switch fabric, the edge device network being formed such that theedge device of the edge device network can be administrated withoutdisruption, modification, or reconfiguration of the node operativelycoupled to the switch fabric; receiving a signal according to anauto-discovery protocol from a switch fabric device of the switchfabric; and sending, to the edge device, a label included in the signalsuch that the edge device sends a data unit via a MPLS tunnel associatedwith the label.
 2. The method of claim 1, wherein the method furthercomprises modifying the edge device without disruption or modificationof the node of the switch fabric.
 3. The method of claim 1, wherein themethod further comprises sending an announcement signal having the labelto other edge devices in the edge device network.
 4. The method of claim1, wherein the signal according to the auto-discovery protocol isreceived after a request, according to the auto-discovery protocol, issent to the switch fabric device of the switch fabric.
 5. The method ofclaim 1, wherein the auto-discovery protocol is at least one of dynamichost configuration protocol (DHCP), link layer discovery protocol (LLDP)or address resolution protocol (ARP).
 6. The method of claim 1, whereinthe label identifies a route from the switch fabric device to the edgedevice.
 7. A non-transitory processor-readable medium storing coderepresenting instructions to be executed by a processor, the codecomprising code to cause the processor to: operatively couple a nodewithin a switch fabric that is coupled to an edge device; operativelycouple to the edge device to define an edge device network separate fromthe switch fabric, such that the edge device of the edge device networkcan be administrated without disruption, modification, orreconfiguration of the node operatively coupled to the switch fabric andsuch that the node of the switch fabric can be administrated withoutdisruption, modification, or reconfiguration of edge devices of the edgedevice network; communicate with the edge device via a multiprotocollabel switching (MPLS) tunnel through the switch fabric; receive asignal, according to an auto-discovery protocol, from a switch fabricdevice of the switch fabric; and send, to the edge device, a labelincluded in the signal and including load balancing information, suchthat the edge device sends a data unit via a MPLS tunnel associated withthe load balancing information.
 8. The non-transitory processor-readablemedium of claim 7, wherein the code further comprises code to cause theprocessor to modify the edge device without disruption or modificationof the node of the switch fabric.
 9. The non-transitoryprocessor-readable medium of claim 7, wherein the code further comprisescode to cause the processor to announce the label to other edge devicesin the edge device network.
 10. The non-transitory processor-readablemedium of claim 7, wherein the signal according to the auto-discoveryprotocol is received after a request, according to the auto-discoveryprotocol, to the switch fabric device of the switch fabric.
 11. Thenon-transitory processor-readable medium of claim 7, wherein theauto-discovery protocol is at least one of dynamic host configurationprotocol (DHCP), link layer discovery protocol (LLDP) or addressresolution protocol (ARP).
 12. The non-transitory processor-readablemedium of claim 7, wherein the label identifies a route from the switchfabric device to the edge device.
 13. The non-transitoryprocessor-readable medium of claim 7, wherein: the switch fabric deviceis configured to be coupled to the edge device network such that theedge device network has a first address domain and the switch fabric hasa second address domain different from the first address domain, atleast one address from the first address domain being dependent on atleast one of a dynamic host configuration protocol (DHCP) request or anaddress resolution protocol (ARP) request.
 14. The non-transitoryprocessor-readable medium of claim 7, wherein: the edge device is afirst edge device, and the switch fabric device is configured to becoupled to the first edge device such that the first edge devicecommunicates with a second edge device via auto-discovery messages,without any other protocol message.
 15. A method, comprising: sending arequest according to an auto-discovery protocol to a first switch fabricdevice of a switch fabric, receiving a response from the first switchfabric device according to the auto-discovery protocol in response tothe request, the response including an indication of an entropy labeland a metric value associated with a second switch fabric device of theswitch fabric or a node operatively coupled within the switch fabric;operatively coupling an edge device to the node so as to define an edgedevice network separate from the switch fabric, such that the edgedevice of the edge device network can be administrated withoutdisruption, modification, or reconfiguration of the node operativelycoupled to the switch fabric and the node of the switch fabric can beadministrated without disruption, modification, or reconfiguration ofedge devices of the edge device network; sending, to the edge device,the entropy label included in the response such that the edge devicesends a data unit via a multiprotocol label switching (MPLS) tunnelassociated with the entropy label; and communicating with the edgedevice via the MPLS tunnel.
 16. The method of claim 15, wherein theentropy label includes load balancing information associated with theMPLS tunnel.
 17. The method of claim 15, wherein the auto-discoveryprotocol is at least one of dynamic host configuration protocol (DHCP),link layer discovery protocol (LLDP) or address resolution protocol(ARP).
 18. The method of claim 15, further comprising: encapsulating thedata unit with a label stack to produce an encapsulated data unit; andsending the encapsulated data unit to the second switch fabric devicesuch that the second switch fabric device uses the label stack todetermine a port of the edge device to which to send the encapsulateddata unit.
 19. The method of claim 15, further comprises announcing thelabel to other edge devices in the edge device network.
 20. The methodof claim 15, wherein the label identifies a route to the edge device.